1. Technical Field
The present invention relates to a music accompaniment apparatus and a method for controlling the same, and more particularly, to a music accompaniment apparatus and a method for controlling the same that is connected to external devices to reproduce audio or video signals and enabled to control a delay of the audio or video signals when connected to a digital device having a delay of the audio or video signals.
2. Discussion of Related Art
The music accompaniment apparatus is a device connected to external devices such as a video monitor or an audio amplifier to produce music accompaniment with a display of caption. Such a music accompaniment apparatus is common in home use and connectible to general household display devices such as TV, monitor, audio amplifier (speaker), or the like. Some variations in configuration are therefore required for the music accompaniment apparatus to cope with the rapid development trends of household display devices.
External devices connected to the music accompaniment apparatus are in continuous development in their configuration and system with the advance of industry. Among the external devices connected to the music accompaniment apparatus, for example, the television which has been developed from black and white television to color television is recently thrust into the high definition and multi-function world with the introduction of digital technologies in stereo sound, remote controller, caption broadcasting, data broadcasting, and so forth.
This trend results in a change of the existing audio or video reproducing devices from analog to digital system. There is hence a strong desire to use external digital devices in connection with the music accompaniment apparatus for audio or video reproduction. But the use of the external digital devices connected to the music accompaniment apparatus confronts some difficulties that may not be found in using the external analog devices.
Generally, the digital devices have more complicated circuitry than the analog devices and require analog-to-digital or digital-to-analog conversion to cause a signal delay. The presence of delay can be demonstrated simply by sending signals to both analog device and digital device at the same time and comparing the reproduction times of the signals.
For example, the digital television reproduces audio and video signals more slowly than the existing analog television. Some digital devices are designed to reproduce external input signals in the analog method, but the digital devices as used herein are confined to reproduce external input signal in the digital method.
In the music accompaniment apparatus, as a user sings along with an accompaniment signal (audio signal) and a caption signal (video signal) reproduced through the external devices connected to the music accompaniment apparatus, the external audio signal generated from the user's vocal performance is fed into a microphone and then reproduced through the external devices.
The music accompaniment apparatus in this case may use one external device for audio signal reproduction, with a different external device for music signal reproduction, or one external device (e.g., TV) for simultaneous reproduction of both audio and video signals.
The time delay of the digital device causes the most serious problem when connecting the music accompaniment apparatus to the external input port of digital device.
The problem caused when using an external analog device (e.g., audio amplifier) for reproduction of audio signal and an external digital device (e.g., TV) for reproduction of video signal is described as follows.
The audio signal or the video signal such as caption signal sent from the music accompaniment apparatus is reproduced from the digital device through an external input port of the digital device, in which case the digital device achieves the signal reproduction inevitably with a predetermined time delay. Contrary to the digital device, the analog device reproduces the audio or video signal without the time delay. It is expediently assumed that the time delay of analog devices is ignorable.
Accordingly, when the music accompaniment apparatus uses an external analog device (e.g., audio amplifier) for audio signal reproduction and an external digital device (e.g., TV) for video signal reproduction, there is the difference between the reproduction time of the audio signal from the external analog device and the reproduction time of the video signal from the external digital device, even though the audio signal and the video signal stored in the music accompaniment apparatus are simultaneously sent to the external analog device and the external digital device, respectively. This does not satisfy the inherent characteristic of the music accompaniment apparatus that the audio signal has the same reproduction time as the video signal.
In the other hand, the problem caused when using one external digital device (e.g., TV) for reproduction of both audio and video signals is described as follows.
The audio and video signals stored in the music accompaniment apparatus have the same reproduction time through the digital device. The digital device may have a circuit for making the same transmission time for the audio and video signals externally applied in a simultaneous time. Contrary to the case of reproducing audio and video signals separately, this case shows that the audio and video signals provided through an external input have the same reproduction time.
The user inputs an external audio signal through a microphone along with the reproduced audio and video signals. The external audio signal input through the microphone is reproduced through the digital device after an elapse of the time delay of the digital device. In this case, the reproduction time of the audio signal internally provided in the music accompaniment apparatus is different from the reproduction time of the external audio signal input through the microphone. The output time of the external audio signal has a significant time difference from the output time of the audio and video signals internally provided in the music accompaniment apparatus.
When an analog device is used for reproduction of both audio and video signals, in which case the time delay is ignored, the reproduction time of the audio and video signals internally provided in the music accompaniment apparatus is almost the same as the reproduction time of the external audio signal input through the microphone.
The scoring system of the music accompaniment apparatus has a problem, when the reproduction time of audio and video signals internally provided in the music accompaniment apparatus or the output time of the audio and video signals from the music accompaniment apparatus is different from the reproduction time of the external audio signal input through the microphone. The same problem occurs when using an external analog device (e.g., audio amplifier) for reproduction of audio signal and an external digital device (e.g., TV) for reproduction of video signal.
The audio signal or the video signal such as caption signal sent from the music accompaniment apparatus is reproduced from the digital device through an external input port of the digital device, in which case the digital device achieves the signal reproduction inevitably with a predetermined time delay. Contrary to the digital device, the analog device reproduces the audio or video signal without the time delay. It is expediently assumed that the time delay of analog device is ignorable.
Accordingly, when the music accompaniment apparatus uses an external analog device (e.g., audio amplifier) for audio signal reproduction and an external digital device (e.g., TV) for video signal reproduction, there is the difference between the reproduction time of the audio signal from the external analog device and the reproduction time of the video signal from the external digital device, even though the audio signal and the video signal stored in the music accompaniment apparatus are simultaneously sent to the external analog device and the external digital device, respectively. This does not satisfy the inherent characteristic of the music accompaniment apparatus that the audio signal has the same reproduction time as the video signal.
The scoring system of the music accompaniment apparatus performs scoring by similarity comparison of the audio signal (accompaniment signal) and the video signal (caption signal) internally provided in the music accompaniment apparatus and the external audio signal A1 input through the microphone in regard to frequency, beat, pitch and pitch contour.
Accordingly, when the reproduction time of the audio signal (accompaniment signal) and the video signal (caption signal) internally provided in the music accompaniment apparatus is different from the input time of the external audio signal A1 input through the microphone, the scoring system of the music accompaniment apparatus inevitably evaluates less similarity in frequency, pitch, pitch contour, or the like between the audio signal (accompaniment signal) and the video signal (caption signal) internally provided in the music accompaniment apparatus and the external audio signal A1 input through the microphone, resulting in a low score.
As described above, the music accompaniment apparatus when connected to at least one external digital device is required to improve various accompanied problems such as the reproduction time (output time) difference between audio and video signals, and erroneous scoring of the scoring system.